1. Field of the Invention
The present invention relates in general to a picture display device such as a television receiver, and more particularly to a picture display device which displays either of two pictures having different aspect ratios on the same screen thereof.
2. Description of the Prior Art
A standard television receiver displays on a screen thereof a picture of which aspect ratio is 4 to 3. On the other hand, a high definition television receiver displays on a screen thereof a picture of which aspect ratio is 16 to 9. That is, the ratio of horizontal width of the picture to vertical height thereof in television is 16:9.
Thus, as is seen from FIG. 9, in case that a high definition picture having the aspect ratio of 16:9 is displayed on a standard television screen having the aspect ratio of 4:3, there are produced two remaining portions or no-signal portions 10 on the upper and lower end portions of the screen. Thus, the remaining portions 10 have no picture thereon.
On the other hand as is seen from FIG. 8, in case that a standard picture having the aspect ratio of 4:3 is displayed on a high definition television screen having the aspect ratio of 16:9, there are produced two remaining portions 12 on the two side portions of the screen.
As is mentioned hereinabove, the remaining portions are produced by the difference between the aspect ratio of the picture and that of the screen. The remaining portions make the screen unsightly when the picture is displayed on the screen.
In view of this, there are proposed display devices, for example, Japanese Patent First Publications Hei-2-104073, Hei-2-179085 and Hei-2-189085, each of which is equipped with two movable screening members to cover or screen the remaining portions of the television screen. However, these conventional display devices equipped with the movable screening members have the following drawbacks.
The movable screening members which are mounted on a front portion of a TV housing are exposed and thus within a TV viewer's reach. Therefore, the movable screening members are necessarily made of plastic or the like which is high in rigidity so as not to be damaged even if the TV viewer adds a substantially large force to the movable screening members. Furthermore, the television receiver is to be necessarily equipped with a safety device to automatically stop the movement of the screening members when the TV viewer touches the screening members by mistake. Thus, the structure of a drive unit to move the screening members complicated due to the installation of the safety device thereon.
The above-mentioned conventional screening members are platelike in shaped slidable in a vertical or horizontal direction so as to move from a first position in which the TV screen is fully exposed to a second position in which the remaining portions of the TV screen are screened thereby. Thus, o a relatively large space must be provided for the sliding movement of the screening members. This tends to impede the development or of a compact TV set.